Communication networks typically include devices, such as firewalls, routers, switches or gateways, which transfer or switch data, such as packets, from one or more sources to one or more destinations. One type of router, known as an edge router, may be placed at the edge of networks to provide an interface between different network domains. Edge routers may include provider edge routers, which may be routers placed at the edge of a service provider's network (e.g., at the edge of an Internet Service Provider (ISP) network), and subscriber edge routers, which may be placed at the edge of a subscriber (e.g., customer) network. In contrast to edge routers, core routers may operate within a network to carry traffic between edge routers.
A service provider that operates a network may transmit subscriber traffic through the network using a number of different possible technologies. In one possible technique, edge routers may forward traffic over the service provider's network as layer 2 traffic in the Open Systems Interconnection (OSI) model, such as by cross-connecting VLANs (virtual local area networks). For example, a subscriber may operate two remote corporate offices, both associated with a single VLAN, that are cross connected using a layer 2 MPLS (multi-protocol label switching) pseudo-wire. Another possible technique to connect subscriber traffic over the service provider's network is to terminate incoming traffic at an edge router and route the traffic using layer 3 routing.
In one existing technique for using both layer 2 forwarding and layer 3 routing, a subscriber may maintain multiple VLANs. One of the VLANs may be dedicated to layer 2 switching and the other to layer 3 routing. However, such an arrangement may not provide a flexible solution that allows subscribers and/or service providers to forward traffic over a network.